Froth flotation of nonsulfide ores



Patented Jan 14, 1947 UNITED STATES, PATENT OFFlCEf FROTH FLOTATION FNONSULFIDE ORES Gregoire Gutzeit, Westport, Conn.

No Drawing. Application September 8, 1943,

Serial No. 501,563

The present invention relates to flotation, and more particularly totherecovery of desired minerals from ores containing the same byapplication of froth flotation methods.

It is an object of the invention to provide an improved flotationprocedure in which, through the application of a chemical principle notheretofore recognized in the flotation art, unwanted gangue materialsare deactivated or depressed and thereby largely eliminated from theconcentrate of desired minerals, thus improving the grade of theconcentrate to a marked degree. It is also'an object of the invention toprovide an improved flotation procedure in which, through theapplication of the same chemical principle, a selective separation canbe made between two valuable minerals.

Froth-flotation is roughly based on the fact that the surface of a givenmineral to be recov ered can be rendered, by the action of so-calledcollectors, more or less water repellent, i. e. aerophil, and amineral-air complex, the specific gravity of which is lower than that ofthe pulp, is thus formed with the air bubbles introduced into the pulp.The binding of the collector to the mineral surface by chemicalreaction, chemoadsorption, adsorption, etc., is due to e1ectrostaticforces, i. e. unsaturated valences, both of the collector itself and ofthe said surfaces.

It is the custom to speak about differential flotation, only in the caseof polymetallic concentration, but most of the usual monometallicflotations are also differential ones, as the gangue has to be preventedfrom floating together with the wanted mineral. If the used collectorhas a tendency to be adsorbed by the gangue (which is particularly thecase of paraflinic oils, fatty acids, fatty alcohols, sulfated= andsulfonated alkyl-compounds, etc., chiefly used in the flotation ofmetallic oxide ores and non-metallic ores), the latter must bedepressed. Roughly, depression consists in the action of preventing thebinding of the collecting reagent to the surface of a certain mineralwhich is not wanted in the concentrate. In the case of monometallicflotation, the gangue minerals which are mostly quartz and silicates,but which may also be carbonates of the alkaline earths, 'must bedepressed. In the case of polymetallic flotation, the gangue, togetherwith other valuable metallic minerals, have to be kept from floating, ora single mineral has to be collected, while others are prevented fromconcentrating in the froth.

Although the usual gangue minerals (with a few exceptions like talc,graphite, etc.) when pure, are naturally more hydrophilic than thevaluable metal-bearing ones, they are easily floated after activationwith metallic cations. Thus,'quartz and most other silicates may beactivated by very small amounts of iron, copper, zinc,

1 lead, nickel, tin, titanium, barium, and some other 4 Claims. (01.209-166) cations, and calcite by barium, copper, iron, and lead saltswhen floated with fatty acid or fatty alcohol collectors at pH valuesvarying with each activating ion. Since in almost every pulp there aresoluble metallic salts present such as dissolved .iron from theball-mill, or copper, zinc, or iron sulfates from the oxidization ofsulfide-minerals, the gangue is always more or less activated and tendsto concentrate in the flotation froth. This is particularly true whenanion active high molecular aliphatic acids and alcohols, or theirderivatives are used as collectors. In order to keep the gangue fromfloating, it is usual to add alkalies such as sodium carbonate, sodiumhydroxide and the like, or sodium silicate, or acids. Alkalies formeasily wettable hydroxides with the activating cations and'increase thehydrophilic character of quartz and the silicates by their tendency toform soluble alkali-silicates. Sodium silicate forms insolublemetallic-silicates and hydrated metallic silica gels with the activatingcations. The acidification of the pulp tends to replace the adsorbedmetallic cations by more positive hydrogen ions which are hydrophilic,and increases the solubility of certain minerals. In addition to theeffect of the alkalies, the use of alkali cyanide for the depression ofthe gangue has been proposed. Cyanide forms soluble complexes with someactivating heavy metal cations, removing them by means ofthis reactionfrom the gangue material.

It will be seen, therefore, that in the flotation of ores, chemical andphysical control is directed, flrstly, toward increasing the flotabilityof the wanted minerals and, secondly. towardminimizing any flotationtendency exhibited by theun- 'wanted gangue minerals contained in theadmixture.

present so as to prevent the activation and flotation of unwanted gangueminerals by the agency of such cations.

Broadly, the invention embraces the addition to a flotation pulp of anorganic compound able to form very stable, water soluble, or insoluble,but hydrophilic, inner complexes (chelate compounds) with the extraneousmetallic cations in solution or adsorbed on the mineral particles,whereby such ions are prevented or inhibited from exerting an activatingeffect on the gangue particles.

Activation of thegangueminerals by metallic ions has been proved thefundamental condition for their flotation with cationic collectors ofthe fatty acid type. A. M. Gaudin and Alfonso Rizo fi 'l P..N.o. 1453,A. I. M. E., February 1942,

, ,latter has to be depressed.

have studied the mechanism of quartz activation takes place in alkalinepulp, after abstraction of barium ions, the optimum ratio of collectorto activating ion being 1:1. The mechanism of this 1 cation adsorptionis postulated to be a result of the ruptured bonds on the quartzsurface, and the maximum barium-ion adsorption is calculated to be 1.7micromol.

Following L. Kraeber and A. Boppel (Metal 8: Erz, XXXI, 19), the cationslisted below will definitely activate quartz within the indicatedpI-I'range:

pH range e s s??? Theyions Ll' Ce++++, Zn++ (ph 7 9 1++ are lesseffective. W. Halbich proved that cal-cite -barium salts using oleicacid as collector, and demonstrated that effective quartz flotationonly' aeration:

iBroadly this second application of the invention embraces the additionto a flotation pulp of an organic compound able to form very stable,

water-soluble or insoluble but hydrophilic innerconiplexes- (chelatecompounds) with the metal lic cations of one of themineral-s,'whereby.suchminerals are prevented from being reacted upon bythe collector, 'andthus inhibited from concentrating in-theflotationfrothl, -It is very. probable that" even normal collectionof;saypchalcocite (copper sulfide) is dueto the-presence'of adsorbed copperions on the surface of the mineral (auto-activation). But even if,thistheory isnot generally admitted, the formation of a hydrophiliccomplex with the metal atoms of the lattice would cause depression.

According to the accepted theory of ionization, soluble salts aredissociated to a greater or lesser extent into their respectivepositively charged cations and negatively charged anions, thus:

cuc1iz= cii+i+2cr Furthermore, these elements are in ,a state ofequilibrium and any change in the concentration of molecular (left) orionic (right),-components results in more or less dissociation,depending upon the direction of displacement.

The Cu++ ions with their two positive, elementary charges are thus in apositionv not only to bind anions with an opposite chargeand so to formnew compounds by the simple process of stoichiometric chemical reaction(by electro- -'valence), but also to'neutralize (by coordination ha beenperformed with collectors which-are mainly fatty acids, higher aliphaticalcohols, or derivatives thercofx; 'I'hese collector's, unlike forexample, the xanthateshsed in the flotation of sulphides, are not veryspecific but have marked tendency to float the whole crude orecomprising .the gang'ue (provided activation tookplace). As

the aim of flotation is selective separation between the valuablemineral and the gangue, the

As stated above, silica, thesilicates, baryte and many light metalcarbonates willunot bind the fatty acidcompounds chemicallyv bythemselves, but only by the intervention of adsorbed cations. If theseextraneous activating cations. can be rendered harmless by a chemicalwhich will'tie them up and remove them asan active factor in theprocess, the gangue minerals will exhibit no tendency to contaminate theconcentrate. As the binding of the cation in an undissociable innercomplex is quite complete, the proposed .aim is fulfilled by the use oforganic reagents able toform .suchcomplex compounds. However, at thesame time, all excess cations are satisfled'and yielded into anundis-sociable complex wherebyreadsorption of the cations by the ganguei precluded.

In the field-of selectiveflotation, the present invention makes possiblethe specific depression v of one or several mineralsgby addition of anex cess (over 0.2'5 kg./t.) of the organic compounds to be described,for reacting with the cations at the surface of the mineral so as toprevent flotation by rendering said surface hydrophilic or water-avid.

valence)- the charge which exists on dipolar compounds, that is,molecules possessing an unbalanced or asymmetric electric field. In theformer case a. new ionic copper compound is formed; in the latter case aneutral structure known asa complex is formed, in which the copper, assuch, possesses a minimum of chemical activity.

are therefore normally able to chemically comblue with, or be adsorbedat the surface of the g'ang'ue minerals, the presence of such moleculargroup as is mentioned above causes these same ions to be withdrawn fromsolution into nonreacting complexes where they become relativelyharmless, thus:

It is well known that in the blue solution formed, the copper is tied upin the complex ion '('Cu(NHa) 4) which is relatively stable and onlyslightly ionized as compared with copperchloride itself. Nevertheless, aslight dissociation of complex cation does occur, thus:

(Cu(NH3) 4) ++2Cu+++4NHa as proved by the fact that the Cu++ canbeprecipitated by Has. Instead of using inorganicdipolar molecules such'asNHa in order to bind-up 7 their molecule certain groups capable ofuniting the actually or potentially activating cations, this inventionis based upon the principle that dissociated metallic ions in solutionin the pulp liquid, or adsorbed on the ganguelparticles, may

be caused to form much mofe stable, undissociable, water soluble orinsoluble, but hydrophilic, inner complexes with specific organicchemicals, which will be set forth hereinafter, which are added to thepulp.

,These specific organic reagents mustpossessin with metals through thereplacement ofv the acidic hydrogen, the metalin the resultant compoundsbeing held in position by a primary or While-Cu, or other metallic ions,in solution this electro-valence, and, on the other hand, other groupsbeing capable of combining with metals through the coordination bond,that is, without thereplacement of hydrogen. If these two functionalgroups are both attached to one single organic radical in theproperrelative position such as to satisfy the Baeyer straintheory, acyclicstructure will be formed which is known as an inner complex or chelatecompound. The metal atom in these four, five or six membered rings ismost frequently attached to a nitrogen, oxygen or a sulfur atom byelectrovalence (salt formation), and it completes the cycle throughcoordinate valence linking it to another functional group containingnitrogen, oxygen or sulfur.

The conception inner complex may b defined for the purpose of thisspecification as a cyclic. chemical structure containingan inorganiccation-(o1 positively charged metal ion) that is bound simultaneously toseveralatoms ina single organic molecule, on the one hand by means ofthe ordinary valence bonds, or electron exchange on the other handthrough the action of an But, if instead of acetic acid, the aminoderivative of the same (amino-acetic acid or glycocoll) is used, aninner complex results from the combination of the cation and the aminoacid (copper glycine) thus:

zcmNrnooo- 211+ Cu"- This compound (complex copper glyconate) issoluble, but the copper atom is bound in such a complete'mann'er that nomore dissociation is possible. As -a result, no measurable free Cu++ions can be detected in the solution, no reaction occurs with HaS,carbonates, caustic or even ammonia, and the solution of the complexshows practically no electrical conductivity;

This class of organic chemicals outlined above is used as reagents ininorganic analysis (especially in the spot test method),'for they are ormay be rendered specific toward certain cations. Some of them have alsobeen proposed as flotation collectors, although mostly without acomplete understanding of the fundamentals involved; for this lastpurpose they must form insoluble, hydrophobic coatings, i. e. anoriented water-repellent film, on the surface of the mineral particle.But, in order to fulfill the aim of disactivating or depressing thegangue by removal of the free or adsorbed metallic ions acting as actualor potential activators according to the present invention, the formedinner complexes or chelate compounds with said cations have to be watersoluble or hydrophilic.

Thus, the present invention discloses the use of organic compoundcapable of forming specific soluble or hydrophilic inner complexes withmetallic ions in solution or adsorbed on the mineral particles,and-thereby preventing such' ions from exerting an activating influenceon the gangue.

In addition to these general conditions required to form a cyclicchelate compound, the latter must be water soluble or hydrophilic'inorder to fulfill the desiredpurpose. The structural fea-v turespromoting water solubility-or hydrophilic character for an organiccompound are not yet completely understood (Refer, in H. Gilman,fOrgaplc Chemistry, John Wiley and Sons, Inc., New

York, N.;Y., 1938, the chapter: Constitution and physical "properties oforganic compounds, by

Wallace R. Brode and John A. Leermakers). Nevertheless, the followingfacts may help to clarify the relation between constitution and wateraflinity:

' Water solubility is not merely a physical, but rather a chemicalphenomenon, which depends upon the ability 'of the soluteto bind dipolarwater molecules (dipole moment of water ,!L=1.84'10 1B e. s.).Hydrophily, .as will .be shown, is closely relatedto solubility.

,Thelsimilarity' between the dissoivee material,

and the molecules of the solvent appear to be very important to thewhole problem of solution,

Because the combining power of the metal atom in a chelate compound issaturated by bonds and complex linkages with several atoms of the sameorganic molecule, inner complexes are mostly non-electrolytes and theattraction of. water molecules (consequently, the hydrationand thesolubility) is inhibited as well as the dissociation. Thus, anthranilicacid (o-aminobenzoic acid) has asolubility of 230 grs. in 100 cc. ofwater at 107.8 0., while its cobalt complex is practically insoluble inboiling water.

Therefore, in addition to the structure required for the formation of achelatecompound (i. e., salt-forming group, complex-forming group andsteric disposition allowing the closure-of a four-, fiveor six-memberedring), the organic depressing reagents, in order to yield solubl orhydrophilic inner tional features which will promote the hydration,

-i. e. groups tending to bind water molecules (or an electric field dueto distortion having the same effect).

Groups which promote afllnity towards water molecules for an organiccompound are, for ,example, the amino, the carboxyl functions. (In thealkanes series, the amino group is generally more active than thecarboxyl group, and the latter more active than thehydroxyl group.) But,

in addition to the presence of these hydration centers, two otherfactors play an important role: (a) the balance between the polar(lyophilic) function and the non-polar (lyophobic) hydrocarbon radical;(b) the configuration of the molecule. i

As a, broad rule,, 'itmay be pointed out that each of thefollowingstructural features will impart water soiubilityjprhydrophilyto an inner complex: 5 1.

Firstly, the chelate "compound (aliphatic or aromatic) must have atleast one free group containing one or both of the elements composingthe water molecule (0 and H). This is particularly the case for thehydroxyand carboxyl-group, and, to a lesser extent, of the aldehyde andcarbonyl-group. It shall be noted that the replacement. of the oxygenatom by sulfur will result complexes, ought to have addiin the formationof less soluble or insoluble complexes. As already pointed out, thelength of the individual carbon chains of the radical in the aliphaticseries must not overbalance the lyophilic function (i. e. contain, forexample, less than '7 carbon atoms for a. hydroxyl group, and less than8 carbon atoms for a carboxyl group in the nalkane series).

The configuration plays an important role, par- The above observationsconcerning structure hold true for all the following points.

Secondly, the chelate compounds containing free inorganic acid radicalslike sul1o-, phospho-, arseno-radicals, and the hydrochlorides ofarcmatic bases, etc., are generally soluble or hydrophilic. This isparticularly the case for the aromatic sulfonates. 1

Thirdly, the trivalent nitrogen atom of amino groups (and heterocycliccompounds) promotes the solubility to an even higher degree than thehydroxyl function.

Thus, n-butane is slightly soluble in water (15 cc. at 17 C. and 772mm..pressure in 100 gr. water); 7.9 gr. n-butyl alcohol (butanol 1)dissolve in 100 gr. water at 20 C.; 5.62 gr. nbutyric acid dissolve in'100 gr. water at 1 0.; whil'n-butylamine is completely miscible withwater (solubility Acetic acid is completely miscible with water.Esterification of the carboxyl group gives insoluble compounds. But theintroduction of an amino-group in an acetic ester brings back thesolubility. :Substitution of the hydrogen atoms of the NHz groupdecreases the It should be noted that, in a-amino acids, esterificationof the carboxyl group increases the solubility. This is due to the factthat, in the free acids, the ionizable hydrogen is linked by a secondaryvalence to the nitrogen (of the amino function), thus blocking acoordination center for water molecules. Esterification liberates theamino group.

EXAMPLE Aminoacetic acid Aminoacetic acid ethyl ester CH2OOO1(1112000055 HzN Hm Soluble 1 gr. in 4.5 grs. water Misciblc with water Aheterocyclic nitrogen atom, even acting as a center of coordination(complex forming group) yields soluble complexes if it belongs to asingle ring (pyridine radical). Thus, a-picolinic acid forms colored,soluble iron (Fe++) complexes, (as well as a silver complex), while thecomplexes of 8-oxyquinoline or a-quinaldinic acid are generallyinsoluble.

Fourthly, if the lyophilic groups as mentioned above, especially thecarboxyl and amino (primary, secondary or tertiary) functions, acting atthe same time as salt-forming and complexforming functions, overbalancethe'radical (i. e., the individual carbon chains) in a compound of thealiphatic series, the complex will be soluble even if no supplementalfree lyophilic group is present. This is the case when no more than 4carbon atoms are attached to the reactive grouping.

As shown above, the amino group (primary, secondary or tertiary) and thecarboxyl group are very powerful solubility-promoting functions.

Solubility ,Simple m al) P 0n the other hand, the hydrogen of thecarboxyl P but Increases 191115 P p y in a group is easily'dissociable(salt-forming group), acids. while the nitrogen of the amino functionand EXAMPLE 0! hetercyclic N-compounds is one of the most (a) activecenters of coordination (complex-forming group). Therefore, organiccompounds with one solubijity Dipole mo amino nitrogen in alpha or betaposition to one o vo Formula m g M 1 carboxyl group, and at least oneadditional amino X 0' or carboxyl group to impart water solubility, i.e. F l C H NE E +1 31 polycarboxylic amino acids, monocarboxylicpolyfiidiiiliiiiiiitj .IIIII? (data-$111 I 81.5 +0194 amino c s, and pcarboxylic po y mi o ac ds. Trim-lemme in which one amino group is in 1or 2 position to one carboxyl function, will yield soluble or CompoundFormula Solubility Amino acetic acid 11 0-0 0 OH 1 gr. in 4.3 gr./l5 O.

Acetic acid monoethylamine HC-C 0 OH Very soluble.

NH(C3H5) Acetic acid dietbylamine HC--C 0 OH Hygroseopic. N(C2Hs)za-Amino ceprolc acid NH; 1 gr. in 48.8 sip 12 c.

CHa(CHi)2 JHCO0E Caproic acid u-monomethylaminc CH:(CH2)2CHC 0 0H 1 gr.in 9.8 gin/13 C.

NH(CH:)

hydrophilic inner complexes, and thus are excellent organic flotationdepressants, through the binding of gangue activating cations intocyclic chelates.

These organic depressants, which are the 5 specific subject of thepresent invention, have the following structural characteristics:

acid derivative (sodium salt) of ethylene diamine is manufactured by theGeneral lDyestufic Corporation, 435 Hudson Street, New York, N. Y.,

Class of Salt-form- Complex-form- Example oi Hydrophilic compounds inggroup ing group reactive grouping group Examples Monoamino poly- CO0H-NH,, =NH, 0 H COOH Aspartic acid (aminosuccinic acid) carboxylic acids.EN g B H0zOOH1OH(NH )COnH H, H Glutamic acid -C('3 HO:C(CH1):CH(NH2)CO2HH NH:

g Iminodiacetlc acid HN- C=O CHSC 01H \CH:CO|H I] Ohelidamic acid (4hydroxy Mine-2.6 C-N= dicarboxyllc we?" 6 OH g t i H H H C H HO C- CO HH0 (1- -00 C-N-(L 2 a N N OH Pyridine dicarboxylic acids 2.3 quinolinic2.4 lutidinie-; I 2.6 dipicolinic-;H2.5 isocinchomeric acids N=J 0 HO-HO C-COOB;

- HO C-GOOH Polyamino mono- COOH NH:, =NH H -NH;, =NH Ornithlne a adiaminovaieric acid) carboxylic acids. EN 1 E mNwri-nonmncoom 11,1 1 6HArginine (a amino-6-guanid lvnleiic acid) H H HaNC(NH)NI.(:)|CH&H:)C0::H ouamcmo acetic age -N -C=0 HaIi- O(=NH)NH -C 00 B:

Polyamino oiy- --CO0H -NH1, =NH, O H -NH: =NH, Uroxanic acid carboxylicacids. EN g 1 EN, (10011 coon f H HzNOOHN-l-eNHO ONE,"

H 0 K ureuine a 0 0H 1 0H H|N0|H =CH-CH(NH;)CO;H NH! 7 v -O 0 OH =NH, NEE: =NH, N Ethylene diamine tetra acetic acid i 4} COOH HOICHIG r HCHzCOrH -c=0 g 7 H 4 HOaHaC 1 I l CHzCOaH It should also be noted that,in addition to osand marketed under the trade name Nullapon the properfunctional groups, the compounds belonging to the aliphatic series donot have individual non-polar radicals any longer than 4 carbons.

As is Well known, most of these aliphatic 7 amino-acids are present(decomposition products of proteins) in the hydrolysis liquor of vegetalmatters (soy-bean, wheat-, sugar 'cane-, beet juices, etc.) and can beextracted therefrom.

amounts of approximately 0.05 kg. per metric ton of ore, and tocondition (agitate) for several minutes.

Dispersants and pH regulators (sodium silicate, sodium carbonate,caustic, hydrofiuosilic acid, sulfuric acid) are then fed as Certainpolyamlno polycarboxylic acids are arm 75 usual and finally theflotation is performed with 11 a properly selected collector such as afatty acid emulsion. A frother may be added, if required.

f As the depressing effect of the organic compound is suflicientlystrong, a paraflin oil (gas oil, kerosene, etc.) can be used in additionto the chemically active collector, reducing substantially the amount ofthe latter. This is a further advantage of the process.

In the following schematic tests, the collecting emulsion was chosen soas to be very unselective byitself, in order to emphasize the depressingaction of the new reagents. This is evidently bad flotation practice,but a convenient experimental procedure. Synthetic ores" (i. e. mixturesof more or less pure minerals) were used, and the flotation performed on30-grs. samples in a. small laboratory cell (capacity: 150 00.), thedilution being 1:5 (distilled water).

Tests I to V were run with a ---65 mesh mixture containing malachite,30% limestoneand 60% quartz (3.77-3.80% C11). The collecting emulsionhad the following composition:

The recovery is good, due to the strong collecting properties of theemulsiornbut the grade of the concentrate is naturally low, asa resultof its lack of selectivity. Th limestone and fine quartz Comments Thegrade of concentrate is only' slightly better than in the foregoingtest, as the depressant was added after the collector, and thereforecould not properly react.

Tssr III Reagents 0.15 cc. 1% solution Nullapon 3---- Cond.? min. 0.1cc. 10% soda ash solutions This test shows the high selectivityobtainable by the proper use of an organic complexing depressant. Thegrade of concentrate rose from 7.21% to 25%, while th tailings droppedfrom 0.37% to 0.18%.

Tnsr IV Reagents 0.15 cc. 1% solution glutamic acid Cond. 3 min. 0.100'. 10% soda ash so1ution sodlum s1h cate 33 B 0.2 cc. 10% vol. sodiumsilicate Cond. 4 min. 1.0 cc. emulsion C0nd1t. 2 mm. 38 B a (1) dropletfrlother B-23 (Amer. Cyanamid Co.) 1.0 emulsion Cond 2 min.

- emu 5111 40 1 droplet frother 13-23 Results 0.3 cc. emulsion W h P RResults eig t er cent ecov. Products gm Cu Grs. Cu per cent W I h PProducts eig t, er cent GT8 Cu Recov.

s. o 0011c 14. 7a 7.21 1.062 95.08 1 gr H per cent Tails 14. 84 0. 37.055

Cone 5.24 19.70 1. 032 93.31 Calc.l1eads 22.51 a 78 1.111 T i 23.86 0.31.014

Cale. heads 29. 09 1. 106 Comments Comments The grade of concentrate is19.70% versus 7.21; the tailings are slightly better than in Test I, dueto the use of an organic complexing departicles were floated. pressantTEST II Tasr V Reagents Reagents 0.1 cc. 10% soda ash solution..- 0.15cc. solution d1. Aspartic 0.2 00. 10% vol. sodium silicate Cond. 4 min.acid Cond. 3 min.

38 B 0.1 cc. 10% soda ash solution 1.0 cc. emulsion Cond. 2 min. 0.2 cc.10% vol. sodium silicate Cond. 4 min. 0.15 cc. 1% solution Nullapon B(Ethyl- 38 B ene diamine tetra acetic acid) Cond. 3 min. 1.0 cc.emulsion Cond. 2 min. 1 droplet frother B-23 5 1 droplet frother 3-230.3 cc. emulsion 0.3 cc. emulsion Results Results Products W35? a? Grs.Cu g f 'g Products WEE? bi Grs. Cu zsg Conc 12. 35 1. 053 94.18 001107.61 13.80 1. 050 04 45 Ta- 11. 23 0.38 .065 Tails 21. 0.28 .001

Cale. heads 29. 58 3. 78 l. 118 Cale. heads 29. 36 1. 111

Comments The grade of concentrate is 13.80 versus 7.21; better tailingsare also obtained.

The next two tests were made with a 65 mesh mixture containing gr.rhodochrosite (manga- 5 nese carbonate) and 25 gr. of silica sand foreach 30 gr. head sample.

Tnsrr VI Reagents 0.25 cc. 10% soda ash solution Cond.4 min. 0.10 cc.10% vol. sodium silicate 38 B Cond.3min. 0.10 cc. 5% monopolsoap (sodiumsalt of highly sulfonated castor oil) 0.05 cc. oleic acid cond'zmm' 0.0300. kerosene; 1 droplet frother 3-23 Results Products WEE? i fi Grs.Mn32: 2

cont 12.38 10.2 1.2027 04.00 Tails 17.14 0.03 0. 079a Cale. heads .29.52 4.54 1. 3425 Comments Good recovery, but the tailings are relativelyhigh and the concentrate is contaminated with fine silica.

Tssr VII Reagents 0.1 cc. 1% solution of Nullapon B Cond. 3 min. 0.25cc. 10% soda ash solution Cond. 4 min. 0.10 00. 10% vol. sodium silicate38 B Cond.3min. 0.10 cc. 5% Monopolsoap 0.06 cc. oleic acid 0.03 cc.kerosene cond'2mm' 1 droplet frother B-23 Results Products gg i g Grs.Mn2:32}

Cone 7.22 17.19 1.2411 94.55 Tails 22. 37 0.32 0.0715 Calaheads 29.594.44 1.8126

Comments Higher grade of concentrate (17.19% versus 10.2%) and bettertailings, due to the use of an organic complexing depressant.

The next test was run with a 30-gr. sample containing 22.5 grs. of amixture of 65% silica and 35% limestone, 2.5 grs. chalcosite (with someas chalcopyrlte), and 5 g'rs. galena. In this case,

an excess of the organic complexing depressant was added, in order tofloat selectively the lead sulfide from the copper mineral.

Tssr V111 Reagents 1.0 cc. 1% solution of Glutamic acid- Cond. 5 min.0.15 cc. 10% soda ash solution 0.1 cc. 10% vol. sodium silicateCond.2min.

38 B 0.2 cc. 1% sodium ethyl xanthate. 1 droplet frother 3-23.

Results Products g P ag Grs.Cu 553" 0 T335 it it 2.92% .6... Cale. heads29. 49 0. 114 1. 803

The following example will further illustrate how the said invention maybe carried out in practice, but the invention is not restricted to thisexample.

EXAMPLE A deslimed (+10 mu) oxide copper ore from Miami (Arizona) hadbeen floated with ethyl xanthate, oleic acid, soda ash, sodium silicateand cyanide as specific depressant (following the Earl Fisher process).The results of the roughing operation werereported as follows by theoperators:

Product Weight gg $9 eg 5312;

lstconc--- 13.9 7.1 0.9809 00.00 1:27 211d 00110.-.- 14.7 1.2 0.170411.80 1:0.8 3rd cone"--- 18.5 0.0 46 0.1203 v 8.05 Tails 52.0 0.400.2110 14.15 Heads 100.0 1.50 1.4952 100.00

The same are was floated without cyanide, but with an added amount 01'ethylene diamine tetra acetic acid (Nullapon B") as follows:

1000 grs. ore 65 mesh were deslimed at 10 microns, yielding 670 grs. ofa sand product with 1.575% Cu. These sands were floated as follows in alaboratory Fagergreen cell:

Nullapon B, 2% solution, 1.0 cc.. Cond. 3min. Soda ash, 10% solution,2.0 cc Silicate 38 B., 10% vol., 1.0 cc Sodium ethyl xanthate, 1%solution, 1.5 cc. Alkanol S. A., 1% (emulsifier), 0.5 cc. Oleic acid,0.3 cc.

Parafiln 011, 0.1 cc.

Kerosene, 0.1 cc.

The results are tabulated below:

Product Weight $3 2 35 gg" Rea. per cent Ratio of c0110,

12. 31. 84 4. 1a. 40 17. 1%} 5 a. 230 14. 85 4. 28 0. 536 see. 10 0. a42. 002

Cond. 5 min. I

The 3rd concentrate can be considered as a contrate and 1.0% in thetails, thus raising the final recovery to 78.2%.

While in the norma flotation a concentrate with 7.1% Cu (Rec. 66.0%) isobtained, the ratio being 1:4.7, the flotation following the presentinvention yields a product with 23.5% Cu (Rec. 73.6%). The tailings are0.46 versus 0.34, and the middlings of the operation first reported arelower than the heads,

Comparison of these results shows that the ratio of concentration isconsiderably raised by conditioning the pulp with a polyaminopolycarboxylic acid.

Therefore, the use, according to the present invention, of organicreagents accomplishing the purpose of gangue depression throughcomplexing detrimental cations into a water soluble or hydrophilicchelate compound constitutes a marked advance in the art of frothflotation, and is highly advantageous in improving the selectivity ofthe collectors, thus improving the grade of concentrate.

What is claimed is:

1. In the concentration by froth flotation oi non-sulfide ores, whichincludes the subjecting of such material when finely ground to flotationin the presence of an emulsion of mineral oil and fatty acid stabilizedby a wetting agent as collector and by the addition of usual modifiers,the step of adding first to the pulp an amount of the order of 0.05 kg'.per metric ton of a noncollecting organic compound containing one aminonitrogen in alpha or beta (1 or 2) position to one carboxyl group andhaving the following general schematic formula:

o (Lt-la (Lila-R H811: Ht s:

where R is a substituted organic aliphatic, aromatic or heterocyclicradical with at least one carboxyl group or one amino nitrogen; saidorganic compound being adapted to react with the gangue activatingcations of the pulp to yield a water soluble or hydrophilic chelatecompound having the schematic general formula:

where Me is a metal atom (monovalent) replacing the hydrogen of thecarboxyl group by electron exchange and linked to the negative aminonitrogen by the coordination bond (dative bond), while the freecarboxylor amino-function or functions attached to R are imparting watersolubility to the chelate compounds.

2. The process as claimed in claim 1, where the depressing organiccompounds are polyvalent amino acids extracted from protein-rich naturalhydrolytes.

3. The process as claimed in claim 1, where the depressing organiccompounds are polyvalent amino acids extracted from protein-rich naturalhydrolytes.

4. The process as claimed in claim 1, where the depressing organiccompound is a polyamino polycarboxylic acid corresponding to the generalformula:

Ac Ac H H /N-RN AcN--R-NAc Ac Ac where R is a lower alkylene radical andAc the radical of an aliphatic organic acid with less than 9 carbonatoms in the chain.

GREGOIRE GUTZEIT.

